The present invention relates generally to fasteners and more particularly to manufacturing of a fastener.
Traditionally, polymeric parts are made by injection or extrusion molding. In such processes, a heated polymeric liquid is inserted into match metal dies under high pressure, after which the dies are internally cooled in order to cure the manufactured parts. Air is vented from the die cavity when the molten polymer is injected therein. Injection and extrusion molding are ideally suited for high volume production where one hundred thousand or more parts per year are required. These traditional manufacturing processes, however, disadvantageously require very expensive machined steel dies, which are difficult and time consuming to modify if part revisions are desired, and are subject to problematic part-to-part tolerance variations. Such variations are due to molding shrinkage during curing, molding pressure differences, part warpage due to internal voids and external sink marks, and the like. The expense of this traditional die tooling makes lower volume production of polymeric parts prohibitively expensive.
It is also known to use stereolithography to produce non-functional polymeric parts. Such conventional stereolithography methods use a laser to create a layered part on a moving platform within a vat of liquid polymer. The part rises from the liquid as it is being made. These parts are extremely slow to produce and impractically brittle.
In accordance with the present invention, a fastener is provided. In another aspect, a fastener is made of layers of material, a light curable material and/or multiple built-up materials. Another aspect uses a three-dimensional printing machine to emit material from an ink jet printing head to build up a fastener. A further aspect provides a method of making a fastener by depositing material in layers and/or a built-up arrangement. Yet another aspect makes a fastener by depositing material in an environment where the fastener is essentially surrounded by a gas, such as air, during the material deposition. A method of making a multi-material and/or pre-assembled fastener is also employed in another aspect. In still another embodiment, direct laser metal sintering is used to create a fastener.
The present fastener and method are advantageous over traditional devices. For example, the present fastener and method do not require any unique tooling or dies, thereby saving hundreds of thousands of dollars and many weeks of die manufacturing time. Furthermore, the present method allows for quick and inexpensive design and part revisions from one manufacturing cycle to another. In another aspect, part-to-part tolerance variations are essentially non-existent with the present fastener and method such that at least ten, and more preferably at least forty, identical fasteners can be produced in a single machine manufacturing cycle. For other aspects of the present fastener and method, multiple head openings, a stationary support for the built-up fasteners within the machine, and the ambient air manufacturing environment allow for increased manufacturing speed, simpler machinery and ease of access to the manufactured fasteners. It is also noteworthy that the present fastener and method are advantageously capable of creating die-locked part configurations that would otherwise be prohibitively expensive, if not impossible, to produce with conventional dies. In other aspects, the present fastener and method reduce post-manufacturing assembly by creating mating parts in a pre-installed or pre-assembled condition within the same manufacturing machine cycle; for example, this can apply to screws, washers, inserts and/or seals. Materials of different characteristics, such as flexibility, tensile strength, hoop strength, chemical resistance, UV fade resistance, or even color can be deposited to create different sections of the fastener at essentially the same time. Additional advantages and features of the present invention can be found in the following description and appended claims as well as in the accompanying drawings.